Add environment var to enable remote debugging
Add environment var to enable remote debugging

The environment var `${JAVA_REMOTE_DEBUG}` is empty by default so no remote debugging.

Enabling it, is easy:
```
echo "Environment=JAVA_REMOTE_DEBUG=-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000" > /etc/systemd/system/multi-user.target.wants/cosmic-agent.service.d/debug.conf
systemctl daemon-reload
systemctl restart cosmic-agent
````

In our CI we can turn in on by default, in generic packaging it is still off.
MissionCriticalCloud/packaging